1. Field of the Invention
The invention pertains to rigging and climbing blocks and, more particularly, to two-part, magnetically-secured climbing and rigging blocks installable and removable from the ground.
2. Discussion of the Related Art
Numerous climbing devices, systems, and methods of support are presently available to the arborist engaged in the care and maintenance of trees. As used hereinafter, the term “arborist” is intended to include any workman working in an elevated position wherein a climbing or rigging block is useful in pursuit of their work. An arborist will employ an aerial lift device or use climbing techniques when working in an elevated position. Climbing techniques involve using one or more climbing ropes in combination with a climbing harness. Aerial lift devices range from large, truck-mounted, systems employing buckets disposed at the end of hydraulic-powered, multi-axis articulating boom to smaller units capable of being towed by small vehicles, a.k.a. “pull behind” models.
Selection of the method and apparatus to be used in a particular application depends on a number of factors including height, location and accessibility of the job site (i.e., tree, foliage and branch density proximate the regions of interest), as well as the nature and amount of work to be performed. For example, an aerial lift may be desirable for use in the removal of a large number of branches from curbside trees which threaten electrical power lines or the like passing nearby; whereas, climbing techniques may be advantageously employed to trim deadwood from an exotic tree species located in a private garden which is otherwise inaccessible by an aerial lift.
Tree crotches, the V-shaped junctions between two limbs or between a limb and the main stem or trunk of a tree, are routinely used to support a climbing or rigging line rope. In one technique, a length of rope is disposed in the crotch and fixedly attached to a climbing harness at one end thereof. The free portion of the rope is attached to the harness with a friction knot, after being passed around the limb or stem. Such a scheme is advantageous in that the arborist may work efficiently in several areas by moving relatively freely about a limited region of the tree through adjustment of the rope loop length supported in the crotch. But such movement routinely results in significant abrasion damage to the bark and often damages the underlying cambium layer of the tree necessary for secondary growth. Such techniques also accelerate climbing rope abrasion and wear, necessitating replacement of the costly rope.
Additional pads of leather or other sacrificial material may be attached to the tree in an attempt to protect both the tree and rope; however, such devices are difficult to employ effectively, due to the tendency of the climbing rope to slip off the pad during use due to changes in orientation and attitude of the arborist relative to the support location. Such devices are also typically unwieldy and bulky, requiring proximate positioning of the arborist for proper manual installation and retrieval.
Protection of the tree from direct abrasion due to movement of the climbing rope may also be effected by the use of lifting slings, similar in configuration to those typically employed in the movement of cargo by cranes or other lifting devices. For example, a continuous loop of rope or webbing may be employed in a conventional choker hitch configuration in a tree crotch or around a tree limb. A climbing rope may pass through the free end loop formed therein to support the arborist as discussed hereinabove. While generally reducing bark abrasion, such a configuration can damage the tree if the load being supported exceeds the capability of the limb, if the constriction of the limb becomes too great, or if the sling slips and moves while under load.
An additional problem with the use of a conventional loop sling in combination with a climbing rope is the problem of installation and removal of the sling in the tree. Conventional methods of ascending the tree, including the use of ladders, climbing spikes or solely ropes which abrade the bark, must often be employed to permit the arborist to reach a suitable location for installation of the sling. Generally, a relatively high altitude location is chosen to afford advantageous support for one or more targeted work regions. Once there, the arborist installs the sling on the limb and couples the climbing rope thereto, at which point the arborist may safely descend and begin work. Since the arborist may be some distance from the original support location after completing work in one region of the tree, a second sling may have to be employed to establish a second suitable support location for completing additional work in another region of the tree. In this manner, numerous slings may be required to adequately perform the desired maintenance on the tree.
In addition to the weight and bulk of the slings which must be carried by the arborist, retrieval thereof is problematic, requiring either individually revisiting the support locations to manually remove the slings or attempting to remove them remotely, for example by pulling on separate ropes attached to the slings themselves. Remote retrieval may be frustrated by catching, snagging or wedging of the loop sling in a tree crotch or on a branch, ultimately necessitating manual removal of the sling. The additional retrieval ropes may also become entangled with the climbing rope, arboreal equipment or other portions of the tree. Further, uncontrolled remote retrieval poses a potential safety hazard both to the arborist and to others working in the vicinity due to the free-falling sling, as well as to the tree which may be damaged if the sling becomes caught on inaccessible limbs, branches or foliage and must be forcibly removed.
One solution to the problems discussed hereinabove is provided in U.S. Pat. No. 5,785,146 for ARBOREAL CLIMBING AND SUPPORT METHOD AND APPARATUS, issued Jul. 28, 1998 to Kenneth Michael Palmer. PALMER provides a variant on a traditional sling wherein rings attached to two ends of a web have two different inside diameters. When used in cooperation with a shot or throwbag and a throw line, the PALMER device may be installed in a tree from the ground. Likewise, when no longer needed, the PALMER device may be extracted from a tree by a person on the ground.
Neither this patent nor any other known prior art, taken singly or in any combination, are seen to teach or suggest the novel climbing or rigging blocks of the present invention.